Italian company Cobelplast is located in northern Milan and is part of the British packaging giant RPC Group. The investment in a new production line from Berstorff in Germany is part of its expansion plan. “We feel welcomed,” said Attila Menghini, general manager of Cobelplast, referring to a new coextrusion line for the production of PET thermoformed sheets, with full care from the design stage to the final operation. Bellsdorf delivered its first production line of PET sheet to the ten hard sheet metal manufacturer in Italy from Italy.

The three-layer sheet production line demonstrates the capabilities of German machinery manufacturers not only in the sheet production sector but also in the processing of undried PET materials. All of the core components of the production line, such as co-rotating twin-screw extruders with vacuum degassing, horizontal three-roll smooth stacking and laminating devices, are from Bellsdorf. This is why the Italian board supplier decided to purchase the special production line. Attila Menghini explained: "We see Bellsdorf not only as our supplier, but also as our partner."

PRC Cobelplast has been manufacturing sheet products for more than 30 years. Their product range includes PS plates with various uses and thicknesses, and since the 1990s, their products have also covered PET sheets. In order to manufacture all these different products, they have so far had four production lines, each with a single-screw extruder. The total annual production capacity reached 13,000 tons. The new production line from Bellsdorf, with almost the same structure, is suitable for the production of PP and PET boards. With it, Cobelplast wants to double its annual production capacity. Menghini stressed: “We are convinced that our investment will be successful. It also points out the direction for the European PET sheet market, which has an annual output of 300,000 tons and an annual growth of 10%.” Cobelplast's customers particularly benefited from the production line The high quality, impeccable quality control and flexibility of the sheet products.

Highlights of the production line
Dieter Ernst, product manager for sheet extrusion at Bernsdorf, explained: “This three-layer sheet extrusion line has several features. With our production facilities, we can produce high-performance, spotless sheets. And this line is designed to produce products from a minimum thickness of 100mm to a maximum of 1.8mm."

The main extruder is the heart of the PET processing line. It is a ZE 90A x 34 D UT machine with a co-rotating twin-screw, with special vacuum degassing technology. Raw materials, such as shredded internal production waste, are directly added to the extruder through a material handling system and a gravity-type charging device, without any need for pre-drying. To ensure excellent end product quality, the extruder has a filtration system that removes deep contaminants. A special back washing system reduces the amount of material needed for back washing. The co-extruder is a single-screw machine that plasticizes the neat PET that is required on the outside of the product for each application. Through the melt line and the feed block, the three melt streams are fed into a wide slot die and from there into the horizontal three-roller grinding device, which is a reliable tool for thin plate production. The leveling device itself has two technical highlights:

First, the device is designed for a nip force of 1500 N/cm;
Second, the roller gap can be adjusted by the motor during production.

Flexibility and quality are decisive
Before the sheet enters the fully automatic tower coiler, it is subjected to surface treatment and cooling in a device equipped with all the fine techniques. They include trimming, thickness measurement, silicidation, and lamination, some of which are necessary to ensure Cobelplast meets the different needs of their approximately 600 customers for sliding agents and lamination. The total production capacity of the new production line is 1200 kg/h, and the maximum width of the sheet is 1500 mm. Four kinds of slit widths can be achieved at the same time.

Attila Menghini emphasized that, thanks to this new production line, RPC Cobelplast is now able to provide custom-made boards of higher quality for the individual needs of customers. In addition to the quality improvement and because of the savings in energy costs without the drying and crystallization steps, the operator of the production line also found the following advantages: Direct treatment and on-line post-treatment help to reduce contact and thus reduce the possibility of contamination. The impeccable process control checks each process parameter and completes the analysis in the event of a failure. Attila Menghini concluded: “This means providing more favorable conditions for our customers in terms of services.” (End)